Project Summary/Abstract: The objectives of the Molecular Pathology Core are: (i) to provide Program Project investigators with access to high-quality, clinically-annotated human bladder tumors that represent the full spectrum of the disease, (ii) to assist investigators with acquisition of human bladder tumors for molecular studies and organoid generation, and (iii) to assist with the morphologic, histopathologic, and genomic characterization of bladder tumors, including those that arise in genetically-engineered mouse models (GEMMs). Core A will play a central role in collecting, annotating, storing, and distributing human tissues as required for each Project, and will assist with histologic, molecular, and genomic analyses of murine and human tumors and organoids, and with the validation of molecular findings from model systems to human urothelial cancer. The particular scientific focus of Core A will be to work with Program investigators to pursue analysis of the temporal sequence in which genomic alterations arise in human bladder cancer. The Aims of the Core are: Aim 1: To acquire and maintain a biorepository of urothelial tumors that reflects all states of disease progression from early non- invasive tumors, to muscle-invasive primary tumors to metastatic lesions, and that reflects the ethnic and gender diversity of patients with urothelial tumors. The Core will work with Program investigators to define the temporal sequence of mutational events in bladder cancer, with a focus on the timing of mutations in epigenetic regulators, such as KDM6A and ARID1A, and genes associated with DNA repair and chemotherapy response, such as ERCC2. The Core will also construct tissue microarrays from bladder specimens, particularly those that have been characterized for genomic alterations, to facilitate validation of key molecular findings from studies of GEMMs and human organoid models to human bladder cancer. Aim 2: To provide expert histopathologic evaluation and molecular characterization of bladder tumors from patients and mice. Core A will play a key role in the molecular characterization of mouse and human urothelial tumors by selecting the most representative tumor regions to be analyzed and by performing macro- or microdissection as needed to enrich for tumor content or to separate non-invasive from invasive or morphologically distinct regions. Core A will also assist the Program investigators with genomic sequencing analyses of tumors, as well as with performing and interpreting H&E, immunohistochemical, and in situ hybridization assays. Integration: Each Project will require contribution from the Molecular Pathology Core to achieve their proposed research aims. Project Leaders will work with the Core to obtain and process paired non-invasive/invasive and primary/metastatic samples and samples collected at distinct times in a patient's disease course to define the timing at which genomic alterations arise during bladder cancer pathogenesis. The Core will also assist in the histopathologic morphologic and molecular characterization of GEMMs organoid models.